Display screen or portion thereof with an animated graphical user interface



FIG. 1 is the front view of the first image in a sequence for a display screen or portion thereof with an animated graphical user interface;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the sixth image thereof; and,

FIG. 7 is the seventh image thereof.

The process or period by which one image transitions to another forms no part of the claimed design. 

CLAIM The ornamental design for display screen or portion thereof with an animated graphical user interface, as shown and described. 